A general problem of paging systems that convert virtual addresses to physical addresses involves a size of pages on a free memory list. Typically a paging system that supports allocation of memory in 64 KB pages does not support a 4 KB page size. In order to be backwards compatible with some currently operating systems and applications, a 4 KB page size needs to be supported. Typically, support of the 4 KB page size is accomplished by allocation of memory in 4 KB units. Pages of size 64 KB may be assembled from 4 KB units by one of several methods. Support of a 4 KB page size by a paging system that supports the 64 KB size in this manner may result in serious inefficiencies in lookup when in the 64 KB page size lookup mode. Typically a whole process or segment must use the same page size, so if a legacy application requests protections or addresses that are aligned on a 4 KB boundary, all of the pages are to be stored as 4 KB pages.